Characterization of magnetic phase in yttrium-doped polycrystalline with and y=0.07 using dielectric and optical parameters

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• 作者：T.N. Ghosh^a ; U.N. Nandi^b ; ^{unphys@scottishchurch.ac.in} ; ^{un_nandi@yahoo.co.in} ; D. Jana^c ; Tapas Paramanik^d
• 关键词：Polycrystalline system ; Dielectric properties ; Scaling ; Master curve ; Exponent ; Magnetic phase transition
• 刊名：Physica B: Condensed Matter
• 出版年：2017
• 出版时间：15 February 2017
• 年：2017
• 卷：507
• 期：Complete
• 页码：134-141
• 全文大小：2039 K
• 卷排序：507

文摘

The dielectric permittivity of yttrium-doped polycrystalline samples La1−x−yYyCaxMnO3La1−x−yYyCaxMnO3 with x=0.05,0.33x=0.05,0.33 and y=0.07 has been measured at frequencies f from 20 Hz to 2 MHz and at temperatures T from 80K to 350K. These samples were prepared in the form of bulk polycrystals(ceramics) by solid state reaction method and characterized by X-ray diffraction technique. With the decrease in temperature, this system exhibits a phase transition from paramagnetic insulating to ferromagnetic metallic at a temperature TMI=225K for x  =0.05 and at 170K for x=0.33. In this report, it is shown that such phase transition can be characterized by the exponents obtained from the scaling analysis of the variation of the real and the imaginary part of the dielectric permittivity ϵ1 and ϵ2 and the loss factor tanδtanδ as a function of frequency and temperature. Results are analyzed systematically from the existing theoretical models and the scaling formalism.